1. Field of the Invention
This invention is related generally to the bending of tubing, and particularly to the formation of bends in rectangular tubing, and the like, that are completely closed and square on the inside of the bend.
2. Description of the Prior Art
Conventional devices commonly employed for forming right-angle and similar bends in metal tubing having a rectangular cross section form an open bend which decreases the strength and rigidity of the element and makes it difficult to weld at the inside corner of the tube at the bend therein in order to additionally strengthen the bent tube.
Prior U.S. Pat. Nos. believed pertinent to this invention are as follows:
1,816,218 July 28, 1931 2,148,748 Feb. 28, 1939 2,516,372 July 25, 1950 2,835,306 May 20, 1958 3,042,099 July 3, 1962 3,073,372 Jan. 15, 1963 3,240,048 Mar. 15, 1966 3,472,055 Oct. 14, 1969